//! 健康检查
//! 
//! 系统健康状态检查和监控

use crate::Result;
use crate::types::HealthStatus;
use std::collections::HashMap;
use std::time::{SystemTime, Instant};

/// 健康检查器
pub struct HealthChecker {
    components: Vec<Box<dyn HealthCheckComponent>>,
}

impl HealthChecker {
    /// 创建健康检查器
    pub fn new() -> Self {
        Self {
            components: Vec::new(),
        }
    }
    
    /// 添加健康检查组件
    pub fn add_component(&mut self, component: Box<dyn HealthCheckComponent>) {
        self.components.push(component);
    }
    
    /// 执行全面健康检查
    pub async fn check_all(&self) -> Result<HealthStatus> {
        let start = Instant::now();
        let mut all_healthy = true;
        let mut details = HashMap::new();
        let mut error_messages = Vec::new();
        
        for component in &self.components {
            match component.check().await {
                Ok(status) => {
                    if !status.healthy {
                        all_healthy = false;
                        if let Some(error) = status.error_message {
                            error_messages.push(format!("{}: {}", component.name(), error));
                        }
                    }
                    details.insert(component.name(), format!("healthy: {}", status.healthy));
                }
                Err(e) => {
                    all_healthy = false;
                    error_messages.push(format!("{}: {}", component.name(), e));
                    details.insert(component.name(), "error".to_string());
                }
            }
        }
        
        let response_time = start.elapsed();
        let error_message = if error_messages.is_empty() {
            None
        } else {
            Some(error_messages.join("; "))
        };
        
        Ok(HealthStatus {
            healthy: all_healthy,
            checked_at: SystemTime::now(),
            response_time_ms: response_time.as_millis() as u64,
            error_message,
            details,
        })
    }
}

/// 健康检查组件trait
#[async_trait::async_trait]
pub trait HealthCheckComponent: Send + Sync {
    /// 组件名称
    fn name(&self) -> String;
    
    /// 执行健康检查
    async fn check(&self) -> Result<HealthStatus>;
}

/// 系统资源健康检查
pub struct SystemResourceChecker;

#[async_trait::async_trait]
impl HealthCheckComponent for SystemResourceChecker {
    fn name(&self) -> String {
        "system_resources".to_string()
    }
    
    async fn check(&self) -> Result<HealthStatus> {
        let start = Instant::now();
        
        // TODO: 实现真实的系统资源检查
        // 1. 检查CPU使用率
        // 2. 检查内存可用性
        // 3. 检查磁盘空间
        
        // 模拟检查
        tokio::time::sleep(tokio::time::Duration::from_millis(5)).await;
        
        let response_time = start.elapsed();
        let mut details = HashMap::new();
        details.insert("cpu_usage".to_string(), "30%".to_string());
        details.insert("memory_usage".to_string(), "50%".to_string());
        details.insert("disk_usage".to_string(), "20%".to_string());
        
        Ok(HealthStatus {
            healthy: true,
            checked_at: SystemTime::now(),
            response_time_ms: response_time.as_millis() as u64,
            error_message: None,
            details,
        })
    }
}

/// Firecracker健康检查
pub struct FirecrackerChecker;

#[async_trait::async_trait]
impl HealthCheckComponent for FirecrackerChecker {
    fn name(&self) -> String {
        "firecracker".to_string()
    }
    
    async fn check(&self) -> Result<HealthStatus> {
        let start = Instant::now();
        
        // TODO: 实现Firecracker健康检查
        // 1. 检查Firecracker二进制是否可用
        // 2. 检查KVM权限
        // 3. 测试VM创建能力
        
        // 模拟检查
        tokio::time::sleep(tokio::time::Duration::from_millis(10)).await;
        
        let response_time = start.elapsed();
        let mut details = HashMap::new();
        details.insert("binary_available".to_string(), "true".to_string());
        details.insert("kvm_permission".to_string(), "true".to_string());
        
        Ok(HealthStatus {
            healthy: true,
            checked_at: SystemTime::now(),
            response_time_ms: response_time.as_millis() as u64,
            error_message: None,
            details,
        })
    }
}

/// 池健康检查
pub struct PoolChecker;

#[async_trait::async_trait]
impl HealthCheckComponent for PoolChecker {
    fn name(&self) -> String {
        "pools".to_string()
    }
    
    async fn check(&self) -> Result<HealthStatus> {
        let start = Instant::now();
        
        // TODO: 实现池健康检查
        // 1. 检查各池的状态
        // 2. 验证池容量和利用率
        // 3. 检查池中沙箱的健康状态
        
        // 模拟检查
        tokio::time::sleep(tokio::time::Duration::from_millis(15)).await;
        
        let response_time = start.elapsed();
        let mut details = HashMap::new();
        details.insert("hot_pool_healthy".to_string(), "true".to_string());
        details.insert("warm_pool_healthy".to_string(), "true".to_string());
        details.insert("cold_pool_healthy".to_string(), "true".to_string());
        
        Ok(HealthStatus {
            healthy: true,
            checked_at: SystemTime::now(),
            response_time_ms: response_time.as_millis() as u64,
            error_message: None,
            details,
        })
    }
}